Paperboard panel substitute for lumber

ABSTRACT

A paperboard panel substitute for lumber, particularly adapted for use as a skid for supporting an object, comprises a plurality of layers of corrugated paperboard forming an inner core, and an outer jacket of solid fiber paperboard enveloping the core and secured thereto. The solid fiber jacket is formed by folding a sheet thereof about the core and adhesively bonding the same thereto. For use as a supporting skid, the panel is pre-formed with an apertured portion to receive a fastening member adapted to be secured to an object to be supported. Such apertured portion includes a knockout section which is displaced by a head on the fastening member to form a countersunk recess and a washer therefor.

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[ 51 Mar. 14, 1972 [54] PAPERBOARD PANEL SUBSTITUTE FOR LUMBER [72] Inventor:

[73] Assignee: Crown Zellerbach Corporation, San Francisco, Calif.

[22] Filed: Apr. 13, 1970 [21] Appl.No.: 27,840

Gary L. Wagner, Covington, La.

2,728,545 12/1955 Hermitage ..108/56 3,436,045 4/1969 Anspaugh ..248/1 19 R 3,026,078 3/1962 Simkins 108/56 FOREIGN PATENTS OR APPLICATIONS 1,144,715 3/1969 Great Britain ..l08/51 Primary Examiner-Chancellor E. Harris Att0rneyStanley Bialos, Corwin R. Horton and William K. Quarles [57] ABSTRACT A paperboard panel substitute for lumber, particularly adapted for use as a skid for supporting an object, comprises a plurality of layers of corrugated paperboard forming an inner core, and an outer jacket of solidfiber paperboard enveloping the core and secured thereto. The solid fiber jacket is formed by folding a sheet thereof about the core and adhesively bonding the same thereto. For use as a supporting skid, the panel is pre-formed with an apertured portion to receive a fastening member adapted to be secured to an object to be supported. Such apertured portion includes a knockout section which is displaced by a head on the fastening member to form a countersunk recess and a washer therefor.

8 Claims, 13 Drawing Figures PATENTEUMAR 14 m2 SHEEI 2 [IF 2 2% w. mafia awn /nvK IA a W PAPERBOARD PANEL SUBSTITUTE FOR LUMBER SUMMARY AND OBJECTS Summarizing the invention, it provides a strong rigid panel which can be employed in many environments as a substitute for lumber, and which is particularly adapted as a substitute for wood slats or skids now commonly employed for attachment to various forms of household appliances to provide firm support therefor in containers for such appliances. The core is formed of a plurality of layers of corrugated paperboard, and advantageously the core has at least four overlying layers of corrugated medium with liners adhesively bonded thereto.

Double wall corrugated paperboard which consists of two layers of corrugated medium, having outer liners and an intermediate liner, is desirably employed. A plurality of congruent layers of such double wall corrugated paperboard may be placed one above the other to provide the core but it is advantageous and desirable to form the core by severing a sheet of double wall corrugated board medially thereof except through one of the outer liners, and to fold the same about the unsevered liner to provide at least four layers of corrugated medium secured to liners.

The entire core is enveloped by a strong jacket formed of relatively heavy solid fiber paperboard which is relatively rigid. A pair of spaced apart double fold lines is provided on the solid fiberboard sheet, which when the sheet is folded about the core form edge walls engaging side edges of the core and which are of substantially the thickness of the core, and also a full panel secured to one side face of the core, and partial panels secured to the opposite side face of the core with their adjacent edges in substantial abutment. In this connection the flutes and ridges of the corrugations of the core are desirably arranged to extend transversely of the length of the panel.

The panel thus formed is a substitute for lumber. It can be used to replace plywood and other forms of lumber parcels, and is particularly adapted to provide a support skid for objects. It can be sawed, and nailed to surfaces as with lumber, and screws can be readily fastened thereto. Moreover, it has the advantages over lumber is not splintering, shrinking or warping, and being without knots that can break out. Also it can be made much lighter than wood of comparable strength, and is more resilient than lumber. Hence, it will absorb shocks more readily; the latter being of particular advantage for use as a skid for supporting household appliances because it will not splinter into pieces that might scratch enameled surfaces ofsuch appliances.

For use as a supporting skid, the panel is preformed with at least one apertured portion to receive a fastening member for attachment to the appliance. The apertured portion includes an enlarged opening in a corrugated layer adjacent the solid fiber outer sheet, which communicates with smaller openings through the panel to thus form a shoulder. A knockout section substantially the size and shape of the enlarged opening, is formed in the solid fiber sheet over the enlarged opening. When the fastening member is screwed or cinched onto the object to which the panel is to be secured, the head thereon causes displacement of the knockout section onto the shoulder. As a result the displaced knockout section provides a washer for the head, and leaves a countersunk recess for receiving the head.

From the preceding it is seen that the invention has as its objects among others, the provision of an improved lumber substitute panel particularly adapted for use as a skid for supporting a household appliance in a shipping container, which is economical to manufacture, strong and rigid, is provided with improved means for securing the panel, and which at the same time has the advantages of wood in being able to be sawed and receive fastening members, and yet none of the disadvantages of warping, splintering, and knots that can be displaced. Other objects will become apparent from the following more detailed description and accompanying drawings in which:

DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a sheet of double wall corrugated paperboard for forming the core of a panel particularly adapted for use as a supporting skid; the view being broken away to shorten the same;

FIG. 2 is a similar plan view but illustrating the sheet of FIG. 1 folded into two congruent layers;

FIG. 3 is a plan view of the outer solid fiber jacket before it is folded about and secured to the core;

FIG. 4 is a transverse sectional exploded view of the core, and the jacket in a position to be folded about the core; the plane of the section being indicated by lines 5-5 in FIGS. 2 and 3;

FIG. 5 is a transverse sectional view of the assembled completed panel; the plane of the section being also indicated by the lines 5-5 in FIGS. 2 and 3;

FIG. 6 is an enlarged fragmentary plan view of the outer solid fiberboard jacket, illustrating a knockout section formed therein;

. FIG. 7 is an isometric view of a pair of panels secured to a household appliance (shown in phantom lines) to provide skid supports therefor;

FIG. 8 is an enlarged transverse fragmentary section taken in a plane indicated by line 88 in FIG. 7, and illustrating a fastening member before it is cinched onto the appliance;

FIG. 9 is a section similar to FIG. 8 but illustrating the fastening member cinched, and the knockout section in the solid fiberboard jacket displaced therefrom;

FIG. 10 is an enlarged transverse sectional view taken in a plane indicated by line 10-10 in FIG. 7;

FIG. 11 is an enlarged fragmentary longitudinal section taken in a plane indicated by line 11-11 in FIG. 7, and illustrating adhesive applied to the raw ends of the panel to moisture proof the same by preventing wicking of water therethrough;

FIG. 12 is a plan view of an unapertured panel which may be employed as a wall panel, or as a substitute for plywood; and

FIG. 13 is a fragmentary transverse section taken in a plane indicated by line 13-13 in FIG. 12.

DETAILED DESCRIPTION The panel hereof which has been advantageously employed as a substitute for a flat oblong lumber skid in supporting a household appliance during shipment in a container, is illustrated in FIGS. 1 through 11, and comprises a core 2 of a plurality of layers of corrugated paperboard. A jacket 3 of heavy solid fiber paperboard completely envelopes the core, being secured thereto by a suitable adhesive. Such jacket comprises a full panel 4, as can be seen best from FIG. 10, adhesively secured to one side face of the core, a pair of partial panels 6, each substantially half the width of the full panel, adhesively bonded to the opposite side face of the core with their adjacent edges substantially in abutment at 7, and edge walls 8 engaging the lateral edges of core 2.

For forming the jacket which is folded about the core, it is provided (FIG. 3) with a pair of longitudinally extending spaced apart double hinge or fold lines 9 obtained by scoring the sheet, with the fold lines of each pair spaced substantially the thickness of the core to provide such edge walls 8 of substantially the same thickness. To enhance rigidity, the sheet for jacket 3 is of solid fiber paperboard which as is well known in the industry, is formed by laminating two or more sheets of solid non-corrugated paperboard together to provide a solid fiber board of desired thickness (caliper) and weight. A suitable caliper and weight for the purpose hereof is between about 60 to point (0.060 to 0.100 in.) which will vary in weight from about 220 to 375 lbs. per thousand sq. ft. Solid fiber board of this character is very rigid and relatively nonfiexible, and the edge walls 8 of the panel will, therefore, form strong beams resistant to bending forces.

Regarding corrugated paperboard core 2, any suitable number of corrugated layers may be employed. Ad-

vantageously, the core is formed of at least four layers of cor rugated medium overlying each other respectively, and of congruent shape substantially the same congruent shape and size as full panel 4 of the jacket between the inner fold lines 9. Conventional so-called double wall corrugated paperboard is desirable, which in unfolded condition comprises two layers of conventional paperboard corrugated medium 11 each adhesively bonded to an outer facing liner sheet 12 and to an intermediate liner 12 as can be seen best from the enlarged views ofFIGS. l and 11.

These layers of corrugated paperboard may be provided by separate pieces of corrugated paperboard but it is advantageous to employ a unitary sheet, as shown in FIG. l, which is folded along a longitudinally extending center line to provide a core of oblong (rectangular) shape shown in FIG. 2. For such folding, the double wall corrugated sheet is severed by slitting along center line 13 (FIG. ll) all the way through except through one outer liner l2, and is then completely folded as shown in FIG. 2 and in enlarged FIG. 10, along such unsevered portion of the outer liner, which thus provides a hinge connection, with the adjacent faces of the folded double wall corrugated board in engagement.

These adjacent faces may have adhesive applied thereto so as to secure them together but this is not necessary. By severing the board in the manner described, and leaving one outer liner as a hinge connection at 13 for the folding, it will be noted from FIGS. 9 and 10 that the side edge of the core at the fold line becomes automatically substantially even without material bulging so as to enable the solid fiber jacket to tightly embrace core 2.

The double wall corrugated paperboard may be of any conventional weight commonly employed known in the industry. A suitable weight for the corrugated medium hereof is about 26 to 33 lbs. per thousand sq. ft. with liners varying in weight from about 30 to 50 lbs. per thousand sq. ft., although this is not critical as liners as high as 90 lbs. per thousand sq. ft have been employed. A suitable weight for skid use is about 26 lbs. per thousand sq. ft. for the corrugated medium, and about 42 lbs. per thousand sq. ft. for the liners, which provides a Mullen test of about 350 lbs. As will be best noted from FIGS. 10 and 11 corrugated paperboard core 2 is so severed and folded that the corrugations and the flutes thereof run transversely with respect to the axial length of the panel.

In forming the panel, as can be seen from FIGS. 4 and 5, the sheet for inner core 2 is folded along fold line 13 to bring the adjacent faces of the double wall corrugated board into engagement; and then with adhesive (indicated at 15 in FIG. 11) applied to the inside face of the sheet for jacket 3, it is folded with full panel 4 positioned over one face of the core and folded along the fold lines 9 to engage edge walls 8 with the side edges of the core and partial panels 6 with the opposite face of the core. When thus assembled, the panel is then passed through conventional compression rollers in a conventional manner to apply pressure and thus effect firm adhesive bonding of the jacket to the core.

With respect to the adhesive, conventional starch adhesive commonly employed in the industry may be used and is preferred. However, any other type of adhesive may be employed, such as thermoplastic or thermosetting resins, and hot melt adhesives. To moisture proof the ends of the panel after the bond has been formed between the core and the jacket, they are coated with moisture proofing material, either by spray or dipping, such as molten wax or plastic material, as is indicated at 14 in FIG. 11.

For use as a skid to support firmly a household appliance 21 such as a refrigerator, TV set, stove or washing machine, shown in phantom lines in FIG. 7, for the purpose of preventing damage to both a paperboard container or the appliance in which it is generally packaged for shipment, the skid is formed with apertured portions 22 to receive fastening members, as is shown in FIGS. 8 and 9. These apertured portions are formed by providing sets of apertures in both the core and the jacket of the panel before they are assembled together. As can be seen from FIGS. 1 through 3, small apertures 23 are formed in the parent core sheet adjacent one side of fold line l3. They register with large apertures 24 at the other side of the fold line when the core is folded.

Small apertures 26 are formed in the full panel 4 of the jacket; and adjacent to such apertures, knockout sections 27 are formed in a partial panel 6 of the jacket. Referring to FIG. 6, it will be noted that each knockout section 27 is formed by a plurality of cuts 28 which are connected together by short uncut sections 29 so that the knockout section can be displaced from the solid fiberjacket upon the application of pressure thereto. The size and shape of the knockout 27 is substan tially the same as the large aperture 24 formed in the core.

With particular reference to FIGS. 8 and 9, it will be noted that the material about each small aperture 23 in the core provides a shoulder 31 adjacent large aperture 24 in the core. As a result when knockout 27 is displaced by pressure, it abuts shoulder 31. Thus, when a fastening member 32, such as a bolt or a screw, is cinched tightly to the appliance support, as shown in FIG. 7, head 33 on the fastening member upon engagement with knockout section 27 will displace the same against shoulder 31. This results in a connection in which the knockout section provides a washer for head 33 and leaves a recess, as shown in FIG. 9, to receive head 33 of the fastening member.

The skid is of rectangular oblong shape being considerably longer than its width and will of course vary in size depending upon the size of the object to be supported by the skid. In the embodiment of the invention illustrated, the skid is about 28% in. long, and about 6 in. wide with an overall thickness of about if; in. The solid fiber paperboard jacket is formed from a sheet of point thickness, weighing about 300 lbs. per sq. ft; and the double wall corrugated board is formed of 42 lb. liner (per thousand sq. ft.) and 26 lb. corrugated mediums (per thousand sq. ft.

As is illustrated in FIG. 12 and 13, the substitute panel for lumber may be any desired shape; and it need not be provided with apertures for attaching the panel where for example, it is to be secured to a wall. In FIG. 13, it will be noted that the outer faces of the panel are formed from the solid fiberboard jacket 41 enveloping and adhesively bonded to the faces of the corrugated paperboard core 42.

lclaim:

1. In a paperboard panel having a core of a plurality of layers of corrugated paperboard and a solid paperboard sheet secured to said core, an apertured portion through said panel for receiving a fastening member for attachment to an object, said apertured portion including an enlarged opening in a corrugated layer adjacent said sheet communicating with a smaller opening to provide a shoulder, a knockout section in said sheet which when the fastening member is cinched to said object is displaced onto said shoulder by a head on the fastening member, and the displaced knockout section provides a washer and forms a countersunk recess for the head.

2. The paperboard panel of claim 1 wherein each side face of the core is adhesively bonded to a solid fiber paperboard sheet, and said knockout section is in one of said solid fiber sheets.

3. A connecting structure between an object, and a panel comprising a core of a plurality of layers of corrugated paperboard, a solid fiber paperboard sheet secured to said core, and an apertured portion through the panel, said apertured portion including an enlarged opening in a corrugated layer adjacent said sheet in communication with a smaller opening which provides a shoulder; a washer of material removed from said sheet in abutment with said shoulder; and a fastening member extending through said apertured portion and secured to said object, and fastening member having a head engaging said washer and which is positioned in a recess resulting from said material removed from said sheet.

4. A substantially rigid paperboard skid for attachment to an appliance to support the same comprising an oblong shaped panel having an inner core of a plurality of layers of corrugated paperboard, an outer jacket of solid fiber paperboard enveloping said core and secured thereto, and having a plurality of apertured portions for receiving fastening members for attachment of the skid to said appliance, each apertured portion including a knockout section in a side face of the solid fiber jacket which when the fastening member is cinched to said appliance is displaced from said face by a head on the fastening member, and the displaced knockout section provides a washer which forms a countersunk recess for the head.

5. A substantially rigid paperboard skid for attachment to an appliance to support the same comprising an oblong shaped panel having an inner core of a plurality of layers of corrugated paperboard with adjacent faces in engagement with each other and terminating in flat side edges extending lengthwise of the skid, an outer jacket of substantially rigid and relatively non-flexible solid fiber paperboard enveloping said core and adhesively bonded thereto; said jacket being folded about said core along spaced apart fold lines providing flat edge panels substantially the thickness of the core substantially congruent with said fiat side edges of the core, a full panel adhesively bonded to one side face of said core and partial panels adhesively bonded to the opposite side face of the core with their adjacent edges substantially abutting, and a plurality of spaced apart apertures extending through the skid between the ends thereof for receiving fastening members for attachment of the skid to the appliance.

6. The skid of claim 5 wherein said solid fiber paperboard of the outer jacket is about 60 to point in thickness weighing about 220 to 375 pounds per thousand square feet.

7. The skid of claim 5 wherein said corrugated paperboard comprises double wall corrugated paperboard having outer paper liners, a pair of corrugated mediums, and an intermediate liner between said corrugated mediums; and said double wall corrugated paperboard is severed except through an outer liner to provide a hinge which is folded to form four layers of corrugated medium.

8. The skid of claim 5 wherein said solid fiber paperboard for the outer jacket is about 60 to 100 point in thickness weighing about 220 to 375 pounds per thousand square feet, and the ends of the skid are coated with moisture proofing material. 

1. In a paperboard panel having a core of a plurality of layers of corrugated paperboard and a solid paperboard sheet secured to said core, an apertured portion through said panel for receiving a fastening member for attachment to an object, said apertured portion including an enlarged opening in a corrugated layer adjacent said sheet communicating with a smaller opening to provide a shoulder, a knockout section in said sheet which when the fastening member is cinched to said object is displaced onto said shoulder by a head on the fastening member, and the displaced knockout section provides a washer and forms a countersunk recess for the head.
 2. The paperboard panel of claim 1 wherein each side face of the core is adhesively bonded to a solid fiber paperboard sheet, and said knockout section is in one of said solid fiber sheets.
 3. A connecting structure between an object, and a panel comprising a core of a plurality of layers of corrugated paperboard, a solid fiber paperboard sheet secured to said core, and an apertured portion through the panel, said apertured portion including an enlarged opening in a corrugated layer adjacent said sheet in communication with a smaller opening which provides a shoulder; a washer of material removed from said sheet in abutment with said shoulder; and a fastening member extending through said apertured portion and secured to said object, said fastening member having a head engaging said washer and which is positioned in a recess resulting from said material removed from said sheet.
 4. A substantially rigid paperboard skid for attachment to an appliance to support the same comprising an oblong shaped panel having an inner core of a plurality of layers of corrugated paperboard, an outer jacket of solid fiber paperboard enveloping said core and secured thereto, and having a plurality of apertured portions for receiving fastening members for attachment of the skid to said appliance, each apertured portion including a knockout section in a side face of the solid fiber jacket which when the fastening member is cinched to said appliance is displaced from said face by a head on the fastening member, and the displaced knockout section provides a washer which forms a countersunk recess for the head.
 5. A substantially rigid paperboard skid for attachment to an appliance to support the same comprising an oblong shaped panel having an inner core of a plurality of layers of corrugated paperboard with adjacent faces in engagement with each other and terminating in flat side edges extending lengthwise of the skid, an outer jacket of substantially rigid and relatively non-flexible solid fiber paperboard enveloping said core and adhesively bonded thereto; said jacket being folded about said core along spaced apart fold lines providing flat edge panels substantially the thickness of the core substantially congruent with said flat side edges of the core, a full panel adhesively bonded to one side face of said core and partial panels adhesively bonded to the opposite side face of the core with their adjacent edges substantially abutting, and a plurality of spaced apart apertures extending through the skid between the ends thereof for receiving fastening members for attachment of the skid to the appliance.
 6. The skid of claim 5 wherein said solid fiber paperboard of the outer jacket is about 60 to 100 point in thickness weighing about 220 to 375 pounds per thousand square feet.
 7. The skid of claim 5 wherein said corrugated paperboard comprises double wall corrugated paperboard having outer paper liners, a pair of corrugated mediums, and an intermediate lineR between said corrugated mediums; and said double wall corrugated paperboard is severed except through an outer liner to provide a hinge which is folded to form four layers of corrugated medium.
 8. The skid of claim 5 wherein said solid fiber paperboard for the outer jacket is about 60 to 100 point in thickness weighing about 220 to 375 pounds per thousand square feet, and the ends of the skid are coated with moisture proofing material. 